As a conventional drowsiness detector, for example, one disclosed in Patent Document 1 is known. A drowsiness detector described in Patent Document 1 determines whether or not a driver is in a nap state by measuring an index (pulse or the like) indicating the conditions for determining drowsiness of a driver, extracting from the index the feature value which changes with drowsiness of the driver, and comparing the feature value with a threshold value. When extracting the feature value from the pulse, an amplitude power spectrum is generated by performing Fourier transform on the time-series data of a pulse period, the time-series data of a pulse fluctuation is acquired by performing integration processing on the amplitude power spectrum, differential processing is performed on the time-series data of the pulse fluctuation, a threshold value is calculated from the average value and the standard deviation of differential values of the pulse fluctuation, and the excess of the differential value of the pulse fluctuation over the threshold value is extracted as the feature value.
Citation List
Patent Literature
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2008-35964